The overall objective of the proposed research is to understand that mechanism of motor control which pre-programs the final position of a movement. The main experimental focus will require human subjects to make extensions and flexions of the forearm, or to maintain the arm at a fixed position. Usually, but not always, the arm pointing will be done to a visual target, but without sight of the limb. External forces will be added during some conditions. Experiments will be designed to measure arm trajectory, external forces, velocity, and electromyographic (EMG) activity of biceps and triceps as recorded from bipolar surface electrodes. The experimental research plan is linked to a theoretical framework for the preprogramming of final position. A goal is to link the data and theory with respect to the quantitative relationships between the EMG activities of the flexors and extensors for the elbow joint; the biomechanical properties of these muscles; external forces; and the final position of the forearm.